1. Field of the Invention
The present invention generally relates to drive assemblies for sickle bars of mowing implements and, more particularly, to a drive motion transmitting assembly for driving a sickle bar.
2. Description of the Prior Art
Many mowing implements from large self-propelled and tractor-pulled swathers and combines to small hand-guided mowers employ an elongated sickle bar. The sickle bar typically has a row of sickle knives reciprocally driven relative to a plurality of stationary sickle guards to cut materials ranging from stalk crops to grass and weeds.
A Pitman-type drive motion transmitting assembly is typically utilized to translate a rotary drive motion of a rotating drive shaft into a reciprocatory drive motion which is applied to one end of the sickle bar. The Pitman-type drive motion transmitting assembly has an arrangement of components which often impose such intense shocks and stresses on the sickle bar that cracks are generated at the location where the assembly connects to the sickle bar. Such cracks will lead to early fracturing and thus there is a need for frequent repairs to the sickle bar. Also, an intense level of vibrations are typically set up in the frame of the implement by the Pitman-type drive motion transmitting assembly which, particularly in the case of hand-guided mowing implements, are transmitted to the handlebars of the mowing implement, providing discomfort to the hands and arms of the operator and making it difficult for the operator to control of the movement of the mowing implement.
Over the years, motion transmitting assemblies of many different designs have been proposed in the prior patent art for reciprocally driving the sickle bars of small hand-guided mowing implements. Representative of these prior art drive motion transmitting assemblies are the ones disclosed in U.S. Pat. No. 1,770,091 to Soss, Clark U.S. Pat. No. 2,269,007, Pazandak U.S. Pat. No. 2,680,340, Kearney U.S. Pat. No. 2,733,565, Minunno U.S. Pat. No. 3,561,200, Cousino U.S. Pat. Nos. 3,657,868 and 4,107,906, Treen U.S. Pat. No. 4,048,791, Nagashima et al U.S. Pat. No. 4,866,921 and Ruder, Sr. U.S. Pat. No. 4,942,725. While most of the drive motion transmitting assemblies of these prior art designs probably function satisfactorily under the limited range of conditions for which they were intended, they are not believed to provide an effective solution to the problems experienced with the Pitman-type drive motion transmitting assembly.
Consequently, a need exists for a still different approach to driving the sickle bar of a mowing implement, and particularly of a small hand-guided mowing implement, so as to reduce, if not eliminate, the problems which have been experienced heretofore.